Xref: utzoo sci.physics:6351 sci.math:6149 sci.electronics:5644 Path: utzoo!attcan!uunet!lll-winken!spl1!ddsw1!corpane!sparks From: sparks@corpane.UUCP (John Sparks) Newsgroups: sci.physics,sci.math,sci.electronics Subject: Re: noise cancellation Summary: out of phase headphones Message-ID: <465@corpane.UUCP> Date: 20 Mar 89 23:38:41 GMT References: <723@wucs1.wustl.edu> <7260@fluke.COM> <453@corpane.UUCP> Organization: Corpane Industries, Inc., Louisville Ky Lines: 33 > In article <453@corpane.UUCP> sparks@corpane.UUCP (John Sparks) writes: > %In article <7260@fluke.COM>, inc@tc.fluke.COM (Gary Benson) writes: > %] The idea behind "anti-noise" as you call it is that you generate an exact > %] replica of the offending noise, except opposite in polarity. > > %Hmm, In theory you can try taking two speakers from a stereo system and > %wire one of them opposite polarity from the other. Then when one cone > %is extending the other is retracting. The two sound sources will be > %180 degrees out of phase with one another. Make sure you feed the same sound > %into both speakers. I just thought of something else. If you took headphones, an amplifier, and a mike and: 1> mounted the mike close to your ears so that it heard what you would hear. 2> then made the output of the amplifier 180 degrees out of phase with the input. Reversing the wires on the headphone speakers would be easiest. 3> wear the headphones and adjust the volume till the anti-sound was just as loud as the sound and it should cancel out. I have an old pair of headphones at home. I might try this on the upcoming weekend. somehow it sounds too simple to work. but what the hey! -- John Sparks | {rutgers|uunet}!ukma!corpane!sparks | D.I.S.K. 24hrs 1200bps ______________| sparks@corpane.UUCP | 502/968-5401 thru -5406 If we weren't supposed to juggle, tennis balls wouldn't come three to a can.